1. Field of the Invention
The present invention relates to spraying devices in general and, more specifically, to an improved spray nozzle assembly which imparts a fan shaped spray pattern and finds particular but not exclusive utility in apparatus for the continuous casting of steel slabs, ingots, billets, or the like. In such apparatus, the casting is conventionally formed in a vertically oriented mold and then withdrawn through a series of closely spaced support rollers where its direction is changed from vertical to horizontal. The support rollers have interspersed cooling devices which apply a coolant spray, usually water, onto the casting for cooling and further solidification thereof. In spray systems of the type known heretofore, problems have arisen because of uneven distribution of the coolant, resulting in non-uniform cooling of the casting. Thus when coolant is applied in excessive amounts on some areas of the casting and sparse amounts, or none, on adjacent areas, cracks may occur in the casting with consequent loss of product.
2. Description of the Prior Art
In hydraulic spray systems of the type previously known, excessive amounts of liquid tend to accumulate in pockets between the rollers and the ingot, creating cool spots which adversely affect the surface of the casting. Such hydraulic nozzles have not demonstrated the ability to provide a consistently uniform spray pattern.
While air-assisted nozzles are available which permit the distribution of relatively fine sprays and consume lesser amounts of water than the hydraulic nozzles, the air-assisted nozzles have generally suffered from the drawback of non-uniform distribution. Larger droplets tend to proceed centrally through the nozzle while finer droplets are dispersed laterally. As a result, greater concentrations of coolant are dispensed axially of the nozzle then at the laterally spaced sides of the spray pattern.
The following prior U.S. patents disclose various forms of coolant spray systems used for cooling the products formed in continuous casting apparatus: U.S. Pat. No. 4,256,168--Hein et al.; U.S. Pat. No. 4,211,272--Schrewe et al.; and U.S. Pat. No. 4,136,527--Kading. The following prior U.S. patent discloses an atomizing spray nozzle over which applicants' present invention represents a substantial improvement: U.S. Pat. No. 4,349,156--Haruch et al.